This paper examines agricultural intensification and its impact on deforestation in a frontier region of the Philippines. Panel data covering the period 1994–2000 are used to study labor demand and resource reallocation in response to lowland irrigation development. Results illustrate how irrigation has led to changes in employment, incomes, and activities at the forest margin. Findings indicate that the off-farm employment opportunities created by irrigation development have helped to reduce rates of forest clearing. Although some initial employment gains have been reversed, wage-induced increases in agricultural productivity in the uplands have reduced forest pressure. Results show that lowland irrigation has had direct, indirect, and lagged effects on rates of forest clearing, and that a virtuous cycle may be at play, with irrigation leading to both poverty reduction and reduced forest pressure.